The present invention belongs to the field of hygienic monitoring of animal containment facilities, particularly IVC (individually ventilated cages) rack systems.
Ventilated shelving storage units are currently known and used for housing laboratory animals, said units enabling a plurality of cages containing animals to be arranged in a tidy manner.
It is also well-known, among those skilled in the art, that the shelving storage units of the kind mentioned above also cater for the need to ensure air circulation inside the cages containing the animals, and prevent said air from being released into the atmosphere.
For this purpose, the cages for containing the animals according to the prior art are equipped with at least two valves, one for delivering and one for discharging the air, while the shelving storage unit or rack system comprises at least one line, or plenum for delivering clean air into the containment cages and one line, or plenum for conveying (removing) the foul air away from the cages.
It is moreover well known that particular care must be taken for the purpose of treating the foul air leaving the cage, because same could be contaminated by pathogens contained in the cages. Moreover, the foul air coming from the cages often contains solid substances in the form of airborne particles and/or micro-particles arising from the solid substances and/or from the dust generally existing in the cages.
Still a further issue relates to the fact that the air to be delivered to the cages must be filtered in advance to comply with the required quality standards so as to ensure that the animals are always kept in an environment with controlled characteristics. For this purpose, the cage rack systems are generally fitted with an air circulation system that delivers air to the clean air plenum only after it has been pre-filtered and usually treated with a HEPA (high efficiency particulate air) filter, which is capable of retaining any airborne particles.
However, the use of IVC rack systems in laboratory animal husbandry has posed new challenges relating in particular to effective microbiological monitoring. Generally speaking, monitoring microbiological conditions (in the following “microbiological monitoring” for the sake of conciseness), in particular of SPF (Specific Pathogen Free) animals, is based on international standards, which have been established by scientific societies in the international laboratory science community.
As an example, in Europe and in the United States microbiological monitoring standards are established by the FELASA (Federation of European Laboratory Animals Science Association) and by the ACLAM (American College of Laboratory Animal Medicine), respectively. As it is known, it is very important to prevent entry into the cages and spread among the cages of unwanted infectious agents, such as for example bacteria and viruses, and therefore the use of individually ventilated cage (IVC) rack systems in laboratory animal husbandry has dramatically increased in the last years. In fact, IVCs not only allow for a control of environmental conditions such as humidity and temperature, they also allow to provide each cage with filtered air, which protects the animals in the cages from airborne infectious or other noxious particulate agents present in the environment.
Microbiological monitoring of animals requires a regular analysis for the presence of infectious agents which may be particle-associated or air-borne. In fact, although housing of animals in IVC rack systems reduces the risk of infection from the environment, routine handling operations such as, for example, changing of bedding and experimental handling of animals, (usually carried out in changing stations such as laminar flow hoods or the like), or even in an unprotected environment, still harbors a risk of exposing the animals to environmental conditions and infectious agents and, thus, to infections.